Inhibition of USP22 by miR-200b-5p represses gastric cancer cell proliferation and migration by targeting the NF-κB signaling pathway

Abstract

Gastric cancer (GC) is an aggressive tumor type with an intricate pathogenesis and limited therapeutic options. Ubiquitin-specific protease 22 (USP22) is a protein implicated in cell proliferation, metastasis, and tumorigenesis. However, the regulatory mechanisms governing USP22 in GC are still not fully understood. In this study, we perform bioinformatics analysis to identify conserved miRNA recognition sites for miR-200b-5p within the 3′UTR of USP22. Validation via luciferase reporter assay confirms the transcriptional regulation of USP22 by miR-200b-5p. Overexpression of miR-200b-5p markedly inhibits the proliferation and migration of GC cells in vitro and suppresses tumor growth in vivo. Conversely, ectopic expression of USP22 reversed this effect by modulating the NF-κB signaling pathway. Additionally, qPCR analysis reveals an inverse correlation between the miR-200b-5p level and USP22 expression in GC. Collectively, our findings indicate that miR-200b-5p-mediated inhibition of USP22 attenuates cell proliferation by targeting the NF-κB signaling pathway in GC, suggesting that miR-200b-5p and USP22 could serve as potential diagnostic or therapeutic targets for gastric cancer and other related human diseases.

1. Introduction

Gastric cancer is one of the most aggressive malignant tumors. It is the second leading cause of cancer-related death worldwide and the fourth most commonly diagnosed cancer [1]. Treatment for GC is still limited due to a lack of effective targets. Surgical resection remains the most effective treatment approach, although recurrence rates postsurgery in many patients remain high, and the five-year survival rate is less than 20% [1–3]. Owing to the complex pathogenesis and numerous pathogenic factors of GC, the potential molecular pathways involved in its development are not fully understood.

USP22 is a member of the ubiquitin-specific processing enzymes on human chromosome 17 that encodes an approximately 66 kDa protein product. USP22 is a subunit of the hSAGA complex that regulates a series of biochemical reactions in cells, mainly through deubiquitination modification, including cell growth, metabolism, tumor formation, the cell cycle, transcriptional activation, and signal transduction. Recent studies have shown that USP22 is involved mainly in tumorigenesis by regulating factors such as Bmi-1, MYC, FBP1, and TRF1 [4–9]; however, how USP22 regulates and participates in tumorigenesis is still unclear.

MicroRNAs (miRNAs) are a type of endogenous, single-stranded, noncoding chromosomal RNA that exerts crucial regulatory functions in cells by explicitly targeting the messenger RNA (mRNA) 3′ untranslated region (UTR), causing mRNA degradation and affecting translation. miRNAs regulate pathways that affect development, virus defense, hematological processes, organ formation, cell proliferation and death, fat metabolism, etc., and may act as oncogenes or tumor suppressors [10–13]. Previous research has demonstrated that USP22 is a target of microRNA-362-3p, which inhibits retinoblastoma growth by reducing the deubiquitination of LSD1 [14]. Moreover, another study suggested that the A1BG-AS1/miR-148a-3p/USP22 axis controls osteosarcoma cell growth and metastasis by stabilizing SIRT1 expression [15]. Additionally, microRNA-30e-5p inhibits the tumorigenesis of non-small cell lung cancer by regulating USP22-mediated Sirt1 [16]. All these data suggest a robust regulatory connection between microRNAs and USP22.